"Peer-Assisted Learning Strategies" is a peer-tutoring program for grades K-6 that aims to improve student proficiency in math and other disciplines. This report focuses on "Peer-Assisted Learning Strategies" for math. The math program supplements students' existing math curriculum and is based on peer-mediated instruction, a process whereby students work in pairs or small groups to tutor each other. During tutoring sessions, students work together on worksheets that target specific math skills, with one student designated to correct his or her partner's errors, award points for correct responses, and provide consistent encouragement and feedback. The program uses videos and teacher-provided scripted instruction to train students to engage in peer tutoring. Developers recommend that students participate in peer-tutoring sessions two to three times a week for approximately 30 minutes per session. The What Works Clearinghouse (WWC) identified 13 studies that investigated the effects of "Peer-Assisted Learning Strategies" on the math performance of elementary school students. The WWC reviewed all of those studies against group design evidence standards. One study (Fuchs, Fuchs, Yazdian, & Powell, 2002) is a randomized controlled trial that meets WWC evidence standards without reservations. The study is summarized in this report. Four studies do not meet WWC evidence standards. The remaining eight studies do not meet WWC eligibility screens for review in this topic area. Appended are: (1) Research details for Fuchs et al. (2002); (2) Outcome measures for each domain; (3) Findings included in the rating for the mathematics achievement domain; and (4) Description of supplemental findings for the mathematics achievement domain. A glossary of terms is included. (Contains 4 tables and 4 endnotes.)